THERE are many factors that affect the ultimate performance of a growing/finishing pig, including genetics, health status, environment, nutrition and feed availability.

Feed must be easily available to the pig in order to capitalize on improvements being made in these other areas that affect performance.

Researchers previously have reported that feed wastage varies widely and can be as high as 30%. Other researchers have shown that too little feeder space, or too narrow of a feeder adjustment, can limit feed intake and performance.

If feed access is limited, pigs tend to spend more time at the feeder, resulting in fewer pigs having access to the feeder. On the other hand, having too much feed and/or feeder space results in increased feed wastage.

More recent research reports indicate that approximately 50% feeder pan coverage is optimum for both average daily gain and gain:feed. Numerous studies have shown that variation in performance could be attributed to differences in the diet form, feeder design and bodyweight range of the pigs being evaluated. The challenge of defining and standardizing the optimal feeder space and adjustment has been difficult for researchers to accomplish.

Swine researchers A.J. Myers, R.D. Goodband, M.D. Tokach, S.S. Dritz, J.M. DeRouchey and J.L. Nelssen at Kansas State University designed two studies to determine the effects of feeder adjustment and feeder space on the growth performance of finishing pigs.

Both studies were conducted in a totally enclosed, totally slatted, environmentally controlled, mechanically ventilated barn with two identical rooms of 20 pens (2.4 x 3.1 m) each. Each pen was equipped with a dry, single-sided feeder with two 35.6 cm long x 11.43 cm wide feeder spaces and a one-cup waterer to allow ad libitum access to feed and water.

Experiment 1

In experiment 1, 234 growing pigs with an initial bodyweight of 41.5 kg were used in an 89-day study. Pigs were allotted to three experimental treatments of 10 replicate pens per treatment, with eight pigs per pen for nine replicates and six pigs per pen for one replicate. Equal floor space was provided at 0.74 sq. m by adjusting the movable gates.

The three treatments were: (1) a "narrow" feeder adjustment of 1.27 cm, with the agitation plate set at up to 1.91 cm, (2) a "medium" feeder adjustment of 1.91 cm, with the agitation place set at up to 2.54 cm and (3) a "wide" feeder adjustment of 2.54 cm, with the agitation plate set at up to 3.18 cm.

The pigs were fed a four-phase feeding program of a fortified corn/soybean meal diet with 20% dried distillers grains with solubles in meal form. The diet was formulated to meet or exceed National Research Council requirement estimates for 20-120 kg pigs.

Average daily gain, average daily feed intake and gain:feed were determined by weighing pigs and measuring feed disappearance every two weeks of the experiment and at the end of the experiment. A digital photo of each feeder was taken once during each phase. On day 89, the pigs were harvested, and various carcass measurements were obtained.

Table 1 summarizes the performance results of the 89-day study.

The researchers provided the following interpretations of the results from experiment 1:

* Increasing the feeder gap increased average daily gain and average daily feed intake, which were optimized in treatment 2.

* As the feeder gap increased, feeder pan coverage was increased, which did not affect average daily gain but did increase average daily feed intake. Gain:feed tended to decrease as the feeder gap increased.

* The carcass criteria evaluated did not differ among pigs fed any of the different feeder gap settings used in this experiment.

Experiment 2

In experiment 2, 288 growing pigs with an initial bodyweight of 37.2 kg were used in the 91-day study. The pigs were allotted to four treatments (Table 2) of eight or 16 pigs per pen and six pens per treatment.

To provide equal floor space among the eight or 16 pigs per pen, the movable gating was adjusted at the start of the experiment to 0.74 sq. m per pig. The diets fed, weighing procedures and photos of each feeder were the same as described in experiment 1.

* Pigs on treatments 2 and 4 had increased feeder pan coverage compared to pigs on treatments 1 and 3.

Proper feeder adjustments have been shown to be an effective method of decreasing feed wastage and improving feed efficiency. In these two experiments, there was approximately a 4-5% improvement in gain:feed with the "narrow" opening compared to the "wide" opening. This represents approximately 12-15 kg of feed per pig with a typical 100 kg of bodyweight gain and a 0.333 gain:feed ratio.

A finding from these two studies was that as pigs gain bodyweight, the feeder gap should be decreased to reduce feed wastage. Also, previous research results have shown that young pigs eat slowly and, thus, spend more time at the feeder compared to older pigs. As feed becomes more difficult to access from the feeder, pigs compensate by spending more time at the feeder, which results in fewer pigs being able to obtain feed.

These two studies used one specific type of feeder. Therefore, feeder pan coverage recommendations could vary with different types of feeders (i.e., dry versus wet/dry), diet form (i.e., meal or pellets), diet formulations and degree of diet flowability (i.e., effects of humidity and dry matter content). Even in these two studies, the feeder pan coverage varied approximately 8% for the same feeder gap setting.

The Bottom Line

The results of these two experiments indicate that pigs from approximately 37 kg to 70 kg in bodyweight need a larger feeder gap (approximately 60% feeder pan covered) to maximize average daily gain.

For pigs from approximately 70 kg to 130 kg, the feeder gap needs to be decreased (approximately 30% feeder pan covered) to reduce feed wastage and optimize growth.

Feeder pan coverage appears to be the best indicator of proper feeder adjustment across the many variables involved in providing feed to the pig.

Reference

J. Anim. Sci. Vol. 90, No. 12.

1. Performance results from experiment 1

-Treatment-

Criteria

1

2

3

Avg. daily gain, kg

0.83

0.85

0.85

Avg. daily feed intake, kg

2.51

2.67

2.70

Gain:feed

0.327

0.313

0.314

Avg. feeder pan coverage, %

27.7

58.2

75.0

Carcass measurements

Bodyweight, kg

126.8

128.4

129.4

Hot carcass weight, kg

93.7

95.7

95.5

Carcass yield, %

73.9

74.5

73.8

Fat free lean index, %

48.5

48.7

48.9

Back fat depth, mm

27.1

26.7

26.0

Loin depth, cm

6.21

6.11

6.26

2. Experiment 2 treatments

Feeder pan

Feeder

Agitation

Treatment

space, cm*

gap, cm

plate, cm

1

4.45

1.27/narrow

Up to 1.91

2

4.45

2.54/wide

Up to 3.18

3

8.90

1.27/narrow

Up to 1.91

4

8.90

2.54/wide

Up to 3.18

*The number of pigs per pen was varied by having either eight or 16 pigs per pen. For the 8.9 cm of feeder pan space per pig, pens were stocked with eight pigs per pen. For the 4.45 cm of feeder pan space per pig, two pens were combined with only one feeder for 16 pigs.